Preheat oven to 375 degrees F. In a 15x10x1-inch baking pan combine almonds, walnuts, and pumpkin seeds. Bake about 12 minutes or until toasted, stirring once.
In a small bowl combine rosemary, brown sugar, salt, and cayenne pepper. Stir in melted butter. Drizzle butter mixture over warm nuts; toss to coat. Serve warm or at room temperature. Store in an airtight container for up to 3 days.